Refining mineral oils



June 22, 1943. J, H. MccLlNTocK REFINING MINERAL OILS Filed July 16, 1940 www *Q Q N\ Wm *Q\ 2 N Q. QN

Patented June 22, 1943 REFINING MINERAL OILS John H. McClintock, Cranford, N. f.'I., assignor to Standard Oil Development Company, a corporation of Delaware e Application July 16, 1940, Serial No. 345,698

Claims.

The present invention relates to the refining of mineral oils. The invention is more particularly concerned with an improved distillation process by which a petroleum oil may be frac- The feed oil is passed through heat exchanger I6 and introduced into Ydistillation unit I by means of lines Il and I8. Temperature and pressure conditions are maintained in distillation tionated in a series of distillation units in an 5 unit I, adapted to remove overhead -by means of eiiicient and economical manner. In accordline I9 a relatively 10W bOiling DeifOleIlm 011 ance with the present process, a petroleum oi1 is fraction. In accordance with the presentV procdistilled into fractions in a series of distillation ess, a portion of the feed oil withdrawn by means units'in a manner in which the reux and deof line 9 by-passes heat exchanger I0 by means sired end point of the overhead product from l0 of line 2li and is introduced into the upper secthe respective units is secured by the introduction oi distillation unit I by means oi' line 2|, tion of a relatively small portion of the feed at preferably on the second bubble cap plate. The a point above the point at which the total feed unvaporized portions oi' the feed oil flow downis normally introduced. wardly into the bottom sections'of the distilla- It is Well-knownin the art to distill mineral tion tower and into shell still 22 which may be oils, particularly petroleum oils, by various procred by any suitable means. For purposes of deesses. In general these operations all are conscription it is assumed that the shell stills 22, ducted in a manner to produce reuxby a suit- 23, 24, 25, 26 and 2'1 are externally fired. able means. Usually the vaporous overhead The unvaporized portions of the oil are withproducts are cooled and condensed and a pordrawn fromshell still 22 bymeans of line 28 tion of the condensate returned to a top plate and passed to second distillation unit 2 by means g1 the distillattion zlflme. A process ir; which ileof line 29. Temperature and pressure conditions ux is secure in is manner aS We aS Simi ar are adapted to remove overhead by means of line processes of this character, are nO partilllaily 30 a petroleum oil-fraction containing constitusuitable for distillation operations employing a ents boiling in the range above the boiling range number of d1st1 lla t1on umts arrangedln Series of the fraction removed overhead from distillaespecially 1n dlstillation operatlons 1n which tion unit 1; In a Similar marmer the unvap0 @n lqe lIetfleum 011s C Ontammg Constltuents rized portions of thefeed oil are passed succesboiling over a relatively wide range are processed. Sively t distillation units 3 4, 5 and 6 by means I have now d1scovered a method of controlling of lines 3|, 32, 33, and 34, respectively. Vaporend pomtfs of Ovrhead Vapoigus Pmqu ind ized fractions containing progressively higher for Surmg mxnlnun ,Capaci l? m dls 1h? on boiling constituents are removed overhead from opera Ions par. 10u ar y n.1.opera wils m W 1C. a stills 3, 4, and 5 by means of lines 35, 35, and 3l, number of units are utilized, which comprises .i introducing a portion of the feed ou at a point 5 respectively, condensed and combined with the streams removed overhead by means of lines I9 1n the distlllation unit above the point at which and .sa to roduce a m isned t l l the total feed is usually introduced. My invenu t b n. p th .1 pe r9 ,eum 01 prod tion may be readily understood by reference to .cl to lmghimh belmom ful bolimgiaange A the attached drawing, illustrating modications le a we y g ,01 fig Vapfnzed acum 1 5 Fe of the Saum moved from distlllation unit 6 by means o1 line For purposes of description it is assumed that i8 Condened an@ bleflded I50 Produce a petrothe feedr oil is a crude petroleum oil, and that leum fl'affilOH I001l11f1g 111 the heating oil boiling the on is distilled in e series of distnletion units gnl- The uvollzed resldue 1S removed from I, 2, a, 4, s, end s, which contain Suitable dis- 1511 a 101111111 Ymeene 011111@ 39. and further tillation means, as for example bubble cap plates rened Crafcked 01' Otherwise handled in any and the 1ike The feed 011 is Withdrawn from n iannerdeslrable. Reflux is provided in distillaf feed storage vessel 'I by means of pump 8 and non umts 2 3y i and 5 in a' manner Similar t0 passed serially by means of line 9 through heat hat described `with respect to distillation unit l. exchangers lu, Il, I2, I3, I4, and l5 which for 50 Perben 0f the feed 011 is Withdrawn by means the purposes of musi-,ration are shown as partial o f line 20, and introduced into the respective diseondensers maintained in the vapor lines of stills tlllaten units by means 0f lines 40, 4l. 42 and 43. I, 2, 3, 4, 5, and 6, respectively. Condensed re- The present process may be widely varied. In flux is returned to the respective stills by means accordance with the preferred adaptation of the of lines 5I. 52, 53, 54, 55, and 56. 55 present invention, the reflux producing oil is intions from the still from which the highest boiling constituents which are blended with the motor fuel are removed overhead, and to pass the segregated unvaporized fractions in heat exchange with the fresh feed and then to introduce the relatively cool segregated stream of unvaporized fractions into the upper section of the distillation unit from which the petroleum oil fraction boiling in the range above the boiling range of motor fuels is removed overhead. This may be fr accomplished in the process illustrated in the drawing by segrega-ting a portion of the bottoms Vin Ystill 5 by means of line 44, passing the same Yin heat exchange With the feed infexchanger `IES and-introducing Vthe cooled segregated portion into the upper sectionof still 6. I Y

Although it is preferred to introduce the feed oil` into4 the respective stills in the Vmanner described,-under certain circumstances it may be desirabletointroduce at least a portion of the feedoil by means of lines `45, 46,111, 4S, 49 and 50,-1espectively. The invention may be adapted tothe 4processingwof vrelatively narrow boiling fractions. However it .is particularly. applicable in the Ydistillation of a feed oil boiling over a relatively. wide range, as. forexample, a crude petroleum. oilfrom which it is. desired to segregate therelativelylower boiling p etroleum frac: tionsv boiling inthe motor fuel boiling range.. the kerosene boiling range, thegas oil boiling range, and various heating oil. boiling ranges I t is es: socially satisfactory in Operation in, which a aendern fraction boiling in the motor feel, beilirls faire@ arida reireleeml fraction hailing in. the.. @were heling range are segregated. fiom a eine einen@ the' ruimer of dieser@ units may vary considerably and-will depend, to a large Vextent, 'the -ilwloeifngV Vdistilled land-.the particular fractigns it isdesired to 'segre-V gat The amount of'feed introduced in the manner described will depend vupor'i' 'general operating Vc6n-d'it'io'ns and up'onthe character of the feedoil being distilled. In general the Yamount-introduced' as reflux should not exceed 10% of the normal feed to the particular distillation unit and preferably should be below 5%. A desirable op# eration, for example, is to decrease the ratio of feed introduced as reflux to normal feed in the successive distillation units as the temperatures in the units increase. Another preferred modification of the present invention is to Withdraw the portions of feed utilized'as reflux from the mainfeed stream as this ystream is withdrawn from the partial condensers of the respective distillation units.` This operation may be conducted by means of lines 6U; 6I, B2, 63,and 66. Thus the-feed portions introduced into -the successive distillation units are Aof-vanprogressively higher temperature. -Y l In order to more fully illustrate the invention the following examples are given, whichv should not be construed as limitingtheV same in any manner. whatsoever. Y

Cil

EXAMPLE 1 A standard battery of crude stills processing a petroleum crude oil was operated under the following conditions:

Temperatures nF.

Vapor Feed Still Bottoms lines Feed maux Conventional Present distillation process Gravity, A. P. I 60.0 70.8 Engler distillation:

` -I. B. PY.; 126 88 Percent disjil 85 89. 5 F, B. P 318 293 EXAMPLE 2 In another similar series of operationsY the results and inspections on the final products were as follows:

Conventional Present distillation process Gravity, A. P.. I 46.6 55.0 Engle'distillationz I. B. P F.. 208 ,139 Per cent distilled at 257 11.., 7 27 F; B. P L F 51.8 418 From the above it is apparent that an unexpected overall improvement in the distillation operation was secured.

The process of the present invention is not to be limited by any' theory or InodeV of operation but only'by the following claimsin which it is desired to claim all novelty insofar as the prior art permits. Y Y

I claim:

l. Distillation process which comprises passing a petroleum crude oil through a series of distillation units operated at progressively higher temperatures, under conditions in which the feed oil is introduced into an intermediate section of the initial unit and'in which unvaporized portions of the oil are withdrawn from the bottoms of the succeeding units and introduced as feed into an intermediate section of the next succeeding unit, withdrawingrvaporous overhead fractions anda final residue, segregating relatively smallportions of the feed oil and introducing said segregated portions directly intofthe upper sections ofthe respective distillation units at a progressively lower point Vintermediate the points of withdrawal ofthe vaporous overhead fractions and the points at which theA feed is introduced, asthe temperature of the respective stills increases.

2. Process in accordance with claim 1, in which the portions of feed oil introduced into the respective succeeding units are of a progressively higher temperature.

3. Distillation process for the segregation of a petroleum oil fraction boiling in the motor fuel boiling range and for the production of a vaporized fraction boiling above the motor fuel boiling range from a, crude petroleum oil which comprises passing the oil through a series of distillation units operated at progressively higher temperatures, segregating and directly introducing portions of the feed oil into the upper sections of the respective stills, separating a bottoms from the still from which the highest boiling constituents boiling in the motor fuel boiling range are removed overhead, introducing a portion of said bottoms into a succeeding still adapted to remove overhead a petroleum oil fraction boiling in the kerosene boiling range, segregating the remainder of said bottoms Withdrawn, passing it in heat exchange with the feed to the initial still, then introducing the relatively cool bottoms into the upper section of said succeeding still, withdrawing and condensing the overhead fractions.

4. Process in accordance with claim 3 in which the segregated portions of feed oil introduced into the upper sections of the respective stills are introduced at a progressively lower point, intermediate the point of withdrawal of the vaporous overhead fraction and the point at which the feed is introduced, as the temperature of the respective stills increases.

5. Process in accordance with claim 3 in which the segregated portions of feed oil introduced into the upper sections of the respective stills are introduced at a progressively lower point, intermediate the point of withdrawal of the vaporous overhead fraction and the point at which the feed is introduced, as the temperature of the respective stills increases, and in which the ratio of feed introduced as reflux to'normal feed to the respective distillation units decreases as the temperature of the respective stills increases.

JOHN H. MCCLINTOCK. 

